sedimentary
Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, conchoidal fracture, waxy to vitreous luster, and colors ranging from white and gray to brown and black.
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Physical properties
Hardness of 7 on the Mohs scale, conchoidal fracture, waxy to vitreous luster, and colors ranging from white and gray to brown and black.
Formation & geological history
Formed through the chemical precipitation of silica from seawater or the accumulation of siliceous microfossils in marine environments over millions of years.
Uses & applications
Historically used for making stone tools and arrowheads due to its sharp edges when fractured; modern uses include abrasives and decorative landscaping.
Geological facts
Chert was one of the earliest materials utilized by humans for weapon making and starting fires when struck against steel.
Field identification & locations
Identify by its extreme hardness, sharp conchoidal breakage, and waxy sheen; commonly found within limestone and chalk formations worldwide.
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Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary